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Category: particle physics – Page 29

Detecting Ice Structures from Space

Depending on the temperature and pressure, ice adopts one of 20 different crystalline phases. Researchers can typically tell one ice phase from the other using x rays or neutron beams, but such techniques are impractical for studying ice on distant celestial bodies. Thomas Loerting from the University of Innsbruck in Austria and his colleagues have now shown that infrared spectroscopy can discriminate between two types of high-pressure ice [1]. The results suggest that astronomical observatories in the infrared could probe ice-covered planets or moons, revealing information about their geological evolution and potential habitability.

The ice in your freezer is hexagonal ice, but at lower temperatures, higher pressures, or both, other forms can exist. Ice phases are distinguished by the ordering of oxygen atoms and hydrogen atoms. For example, ice V has oxygens arranged in ring structures, while its hydrogens have random (disordered) positions. This phase, which is stable at pressures of 500 megapascals and temperatures of 253 K, is thought to form in the interior of Jupiter’s moon Ganymede, Saturn’s moon Enceladus, and other icy moons.

In the lab, Loerting’s colleague, Christina Tonauer, created ice V, along with a related, hydrogen-ordered version called ice XIII. The team performed near-infrared spectroscopy on both samples and identified several distinguishing features, including a structure-dependent “shoulder” around 1.6 µm, a wavelength associated with stretching modes. According to the team’s calculations, the features are strong enough that astronomical instruments, such as those on the JWST observatory and the Jupiter-visiting JUICE mission, could potentially observe them on a body like Ganymede. “The detection of high-pressure ice phases at or near the surface could point to internal processes such as tectonic activity, cryovolcanism, or convective transport from deeper layers,” Loerting says.

Stars That Shouldn’t Shine Are Pointing Straight to Dark Matter’s Identity

Deep in the center of our galaxy, scientists believe a strange type of star may be quietly glowing—not from fusion like our Sun, but from the invisible fuel of dark matter.

These “dark dwarfs” could act like cosmic detectors, collecting heavy, elusive particles that heat them from the inside. If we find them—and especially if we spot one missing its lithium—it could finally point us toward what dark matter really is.

Dark dwarfs & dark matter basics

“We Might Be Seeing a New Force”: Physicists Detect Possible Fifth Law of Nature Hidden Deep Inside Atomic Structures

IN A NUTSHELL 🔬 Physicists from Germany, Switzerland, and Australia have identified potential evidence of a mysterious fifth force within atoms. 📏 The discovery challenges the Standard Model of physics, which traditionally categorizes forces into four main types. 🧩 Researchers propose the existence of a hypothetical Yukawa particle that could mediate this new force within

Radio signal from the very early universe offers clues about the first stars

Understanding how the universe transitioned from darkness to light with the formation of the first stars and galaxies is a key turning point in the universe’s development, known as the Cosmic Dawn. However, even with the most powerful telescopes, we can’t directly observe these earliest stars, so determining their properties is one of the biggest challenges in astronomy.

Now, an international group of astronomers led by the University of Cambridge has shown that we will be able to learn about the masses of the earliest stars by studying a specific radio signal—created by hydrogen atoms filling the gaps between star-forming regions—originating just a hundred million years after the Big Bang.

By studying how the first stars and their remnants affected this signal, called the 21-centimeter signal, the researchers have shown that future radio telescopes will help us understand the very early universe, and how it transformed from a nearly homogeneous mass of mostly hydrogen to the incredible complexity we see today. Their results are reported in the journal Nature Astronomy.

Could AI help us better understand the universe?

For almost as long as humans have existed, we have been trying to make sense of the cosmos. What started as philosophical musing has, following the advent of the telescope and the ability to look ever farther into space (and ever earlier in time), become a thriving field of research.

Today, scientists seek to understand the properties governing how our universe behaves. These properties are characterized mathematically as so-called cosmological parameters, which fit into our models of the cosmos. The more precisely these parameters can be measured, the better we are able to differentiate between models, as well as validate — or rule out — long-held theories, including Einstein’s general theory of relativity. Because different models can hold vastly different predictions for both our universe’s earliest moments and eventual fate, that differentiation is vital.

To date, some of the biggest challenges include more tightly constraining parameters such as those that determine the precise amount and nature of dark matter, the source of dark energy and the repulsive force that it exerts, and exactly how neutrinos behave.

Magnetism recharged: A new method for restoring magnetism in thin films

Modern low-power solutions to computer memory rely heavily on the manipulation of the magnetic properties of materials. Understanding the influence of the chemical properties of these materials on their magnetization ability is of key importance in developing the field.

A study published in Applied Physics Letters, led by researchers from SANKEN at The University of Osaka, has revealed a technique for recovering magnetism in a degraded spintronics device. This method can be applied to improve the robustness of next-generation semiconductor memory.

Spintronics exploits the spin (and charge) of electrons to process and store memory, and this is achieved practically by stacking layers of thin material films that behave differently under the influence of a magnetic field.

Unveiling hedgehog topological defects in three dimensional glasses

I’ve always been fascinated by how materials break down, especially glasses and polymers that don’t have a regular crystal structure. Unlike crystals, where we understand plasticity through things like dislocations, amorphous materials like glasses are messier. There’s no neat lattice to analyze, so figuring out where and how they deform under stress is a big open question.

In two dimensions, researchers, including my research group and myself, have started using a topological approach—looking at vortex-like patterns in how atoms move or vibrate—to identify weak spots in glasses. This also included slicing 3D glasses to find in the two-dimensional slices. That got me wondering: Could we do something similar in three dimensions, and, crucially, without having to slice the into 2D layers?

In this work published in Nature Communications, together with my postdoc Dr. Arabinda Bera, who performed the analysis, and with my longtime collaborator Prof. Matteo Baggioli, we show that we can. We use a kind of topological defect called a hedgehog, which is a point-like distortion in a vector field—like when tiny arrows in space all point outward or inward, just like the spines of a hedgehog. These kinds of defects are well-known in soft matter physics, particularly in liquid crystals, but we hadn’t seen them applied to 3D amorphous solids before.

Physicists Close In on the Fifth Force That Could Unlock the Mystery of Dark Matter

Scientists are using trapped ions in cutting-edge experiments to hunt for signs of an undiscovered particle that might help unravel the mystery of dark matter. The Standard Model of particle physics offers an exceptionally precise description of the fundamental components that form all visible ma

“Uncharted Waters”: Large Hadron Collider Begins Colliding Oxygen For The First Time

For example, when studying heavier ion collisions and xenon-xenon collisions, scientists at ATLAS saw “jet quenching”, as high-energy particles lose energy as they negotiate the quark-gluon plasma. Jet quenching was not seen in proton-lead collisions, which formed a smaller quark-gluon plasma system.

“Theory predicts we should see the onset of jet quenching in oxygen–oxygen collisions,” Longo added. “If we observe even modest suppression, it could pin down the critical system size at which jet quenching begins.”

Also of interest in these studies is the “collective flow” seen in the collective motion of particles that emerge from the quark-gluon plasma. Studying oxygen collisions could help tell us more about this collective behavior, whilst also telling us about the geometrical structure of oxygen nuclei. Meanwhile, colliding neon could tell us about its structure too, thought to be roughly in the shape of a bowling pin. The shape itself could have an impact on the formation of quark-gluon plasma.

Shape-shifting particles allow temperature control over fluid flow and stiffness

Imagine a liquid that flows freely one moment, then stiffens into a near-solid the next, and then can switch back with a simple change in temperature. Researchers at the University of Chicago Pritzker School of Molecular Engineering and NYU Tandon have now developed such a material, using tiny particles that can change their shape and stiffness on demand.

Their , “Tunable shear thickening, aging, and rejuvenation in suspensions of shape-memory endowed liquid crystalline particles,” published in Proceedings of the National Academy of Sciences, demonstrates a new way to regulate how dense suspensions—mixtures of solid particles in a fluid—behave under stress.

These new particles are made from liquid crystal elastomers (LCEs), a material that combines the structure of liquid crystals with the flexibility of rubber. When heated or cooled, the particles change shape: they soften and become round at higher temperatures, and stiffen into irregular, angular forms at lower ones. This change has a dramatic effect on how the flows.

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